If the USB device does not function properly after your computer or host has been in sleep mode, it is likely that Windows turned off the USB Root hub in order to save power.

To prevent this, follow the steps below (depending on your operating system).

Windows 10 / 8

1. On your keyboard, press the Windows key + X and select Control Panel.
2. Click Hardware and Sound, then click Power Options.
3. Click Change plan settings for the plan you want to change.
4. Click Change advanced power settings.
5. Click the plus sign (+) next to “USB settings” and “USB selective suspend setting” to expand the options and change the setting to Disabled.
6. Click OK to apply the setting.

Note: You may need to disconnect and re-connect your USB device after applying these settings.

Windows 7 / Vista

1. Click the Start button and select Control Panel.
2. Click Hardware and Sound, then click Power Options.
3. Click Change plan settings for the plan you want to change.
4. Click Change advanced power settings.
5. Click the plus sign (+) next to “USB settings” and “USB selective suspend setting” to expand the options and change the setting to Disabled.
6. Click OK to apply the setting.

Note: You may need to disconnect and re-connect your USB device after applying these settings.

Windows XP

1. On your desktop, right-click the My Computer icon and select Properties.
2. Click the Device Manager tab.
3. Expand Universal Serial Bus controllers by clicking the arrow to the left of it.
4. Right-click the first USB Root Hub device and select Properties.
5. Click the Power Management tab.
6. Clear the box next to Allow the computer to turn off this device to save power.
7. Click OK to apply the setting.
8. Repeat steps 4-7 for any remaining devices in the Universal Serial Bus Controllers section with “Root Hub” in the name.

Note: You may need to disconnect and re-connect your USB device after applying these settings.